Merge pull request #5 from andyjp94/patch-2

Changed -vars-file to -var-file in Packer.build()

Author: nir0s

README.md

@@ -34,11 +34,11 @@ packerfile = 'packer/tests/resources/packerfile.json'
 exc = []
 only = ['my_first_image', 'my_second_image']
 vars = {"variable1": "value1", "variable2": "value2"}
-vars_file = 'path/to/vars/file'
+var_file = 'path/to/var/file'
 packer_exec_path = '/usr/bin/packer'
 
 p = packer.Packer(packerfile, exc=exc, only=only, vars=vars,
-                  vars_file=vars_file, exec_path=packer_exec_path)
+                  var_file=var_file, exec_path=packer_exec_path)
 p.build(parallel=True, debug=False, force=False)
 ```
 
@@ -171,4 +171,4 @@ The [sh](http://amoffat.github.io/sh/) Python module is used to execute Packer.
 As such, return values from all functional methods (`validate`, `build`, etc..) other than the `version` method
 will return an `sh` execution object. This is meant for you to be able to read stdout, stderr, exit codes and more after executing the commands. With the progression of `python-packer` less abstract objects will return and more concise return values will be provided.
 
-Additionally, to verify that all errors return with as much info as possible, error handling is done gently. Most errors will raise an `sh` exception so that you're able to interact with them. Again, as this module progresses, these exceptions will be handled properly.
+Additionally, to verify that all errors return with as much info as possible, error handling is done gently. Most errors will raise an `sh` exception so that you're able to interact with them. Again, as this module progresses, these exceptions will be handled properly.